The invention relates to an unwinding device for wound rolls, with a bearing element, two support elements disposed on the bearing element for rotatably holding a wound roll on both sides, and a drive mechanism for moving the two support elements along the bearing element. The two support elements are mounted so that they can move along the bearing element such that, when the two support elements move relative to one another, the spacing between these changes.
Material webs, in particular paper webs in the paper processing industry, are generally delivered and stored in the form of large, heavy wound rolls. When processing material webs of this kind on appropriate machines, these webs are drawn off the wound rolls. These processing machines are therefore provided with appropriate unwinding devices in which the wound rolls are rotatably held on both sides on two support elements disposed on a bearing element. In this case the wound roll is usually clamped without a shaft between the two support elements and held by these during unwinding. The support elements are mounted on the bearing element so that they can move towards and away from one another for loading with a new wound roll, for removing the core of the wound roll following complete unwinding and for setting to different roll widths and adjusting the position in relation to the material web path.
EP 0 909 253 B1 and the corresponding U.S. Pat. No. 6,042,047 A, which constitute the closest prior art on which the present invention is based, disclose an unwinding device for large paper rolls which comprises a frame with four stands and two longitudinal girders, as well as at least one unwinding beam and two support arms each with a clamping head. The support arms are mounted on the unwinding beam so that they can move horizontally and transversely, and are coupled together via a common threaded spindle. A first drive provides for a joint contradirectional transverse displacement of the support arms, and a resultant change in their spacing from one another in order to pick up wound rolls of differing width. A second drive provides for a joint equidirectional transverse displacement of the support arms without changing their spacing from one another, for the relative positioning of the wound roll in the processing machine. Also provided on the frame on both sides for a vertical displacement of the unwinding beam are tension means, preferably in the form of cables, belts or chains, which are fastened to two spindle nuts of a second horizontally disposed threaded spindle, so that the unwinding beam is suspended from the frame via the tension means. This second threaded spindle is rotated by means of a third drive.
EP 0 289 749 B1 and the corresponding U.S. Pat. No. 4,895,314 A disclose a device for unwinding a material web from a roll, in particular a large paper roll for the paper processing industry. In order to rotatably hold a wound roll, this known device also comprises two support arms which are mounted together on a pivot shaft. In order to enable rolls of differing width to be picked up, this known device is also provided with a drive mechanism comprising a threaded spindle by means of which the support arms can be moved in the transverse direction. Also provided is a pivot drive for pivoting the support arms about the pivot shaft, as well as a further drive in order to move the pivot shaft together with the support arms horizontally in the web travel direction. DE 38 25 673 A1 describes a similar unwinding device for large paper rolls which comprises two support arms which are mounted together on a pivot shaft. The support arms are provided with clamping heads which are of a retractable construction in order to be able to pick up new wound rolls.
DE 42 19 518 A1 discloses a device for feeding roll-shaped material to a gluing preparation station. This known device, which is intended in particular for accommodating large paper rolls which are to be unwound, comprises a frame with at least four stands which are connected together by two longitudinal girders. At least one crossmember which can travel in the transverse direction is provided between the longitudinal girders, on which crossmember two support arms are disposed so that they can move horizontally and transversely by means of two trolleys.
The known unwinding devices require in particular a highly complex drive mechanism in order to be able to implement all the desired displacement functions.